Propeller deicer



April 8, 1947.

l... A. WILLIAMS, JR, Erm.

PBOPELLER DE- ICER Filed Harsh 20, 1943 2 Sheeibs--Sheeihl 1 APl'il 3 1947- L. A. WILLIAMS, JR, ErAL 2,418,682

PROPELLER DE- ICER Patented spr. 8, 1947 UNITED STATES PATENT `GFFICE PROPELLER DEICER McCollum,

deceased,

assignor to Stewart- Vlarner Corporation, Chicago, Ill., arcorporation of Virginia Application March 20, 1943, Serial No. 479,896

l2 Claims. l

Our invention relates to propeller de-icers and more particularly to a propeller de-icer wherein internal combustion heaters are located in the hollow blades of an airplane propeller.

In airplane operation, considerabledifficulty is experienced with the formation of ice on the propeller blades under certain conditions of atmospheric temperature and humidity. Attempts have been made in the past to eliminate the formation of this ice by discharging of the engine exhaust gases through passages in the propeller blades with a View to heating these blades suiciently to prevent the formation of ice thereon. Such arrangements have numerous disadvantages and have proved unsatisfactory.

Attempts have also been made to solve the decing problem by installing electric heaters in the propeller blades. Such heaters are heavy and consume greater quantities of current than are readily available, so that a special generator must be installed to furnish the current for such heaters. The addition of this special generator materially increases the weight of the installation and results in a substantial reduction in the power output of the airplane engine where this generator is driven by such engine. Where a special engine is provided to drive the generator, the weight or the installation is still further increased.

An object of our invention is to provide a new and improved propeller de-icer which will supply the desired quantity of heat and which can readily be rendered inoperative when heat for de-icing is not required.

Another object of our invention is to provide a new and improved de-ioer wherein internal combustion heaters are located in the Shanks of hollow Vpropeller blades and are supplied with fuel by a barometric control whichmeters the fuel to furnish the correct amount for constant propeller speed at any altitude.

Another object of our invention is to provide a propeller de-icer `which may be readily installed in an adjustable pitch propeller of the types now in service.

Another object of our invention is to provide a new and improved propeller 'de-icer which requires only a small amount of electrical current for its operation.

Another object of our invention is to provide a new and improved propeller de-icer which may be supplied with fuel from the main fuel tank or tanks of the aircraft or may have its own separate source of fuel supply as desired.

Another object of our invention is to provide a new and improved propeller de-icer which is sturdy, reliable, emcient, and inexpensive to manufacture and install.

Another object of our invention is to provide a new and improved propeller de-icer which requires aminimum of attention on the part of the operator of the aircraft.

Other objects and advantages Lwill become apparent as the description proceeds.

In the drawings:

Fig. 1 is an irregular, sectional View showing our invention applied to a controllable pitch propeller. This view is taken generally on the line l-l of Fig. 3;

Fig. 2 is a transverse, sectional view through one of the propeller blades and is taken` on the line 2-2 of Fig. 1;

Fig. 3 is an irregular, sectional View taken generally on the line 3--3 of Fig. 1; and

Fig. 4 is a View showing a partial, longitudinal section through a propeller blade. This `view is on an 'enlarged scale and-is taken on the line 4 4 of Fig. 2. y In'the drawings, we have shown our invention as being applied to a typical `adjustable pitch propeller of the automatic type wherein weights or other suitable devices are utilized to shiftthe propeller blades to afford a substantially uniform propeller speed for all conditions of operation. In general, this adjustable pitch propeller is i1- lus'trated as comprising three hollow blades Ill, each having-a root or base end i2 rotatably mounted in a bearinglll carried in one of the arms IB of a hub I8. As best shown in Fig. 3, the-hubv|8 is attached by bolts 2i! to the flange 22 of a sleeve 24 having longitudinally extending splines 25 located in longitudinal gro-oves 28 formed in the crank shaft Si! or an extension attached theretoand rotatable therewith. Each of the propeller blades is rotatable for pitchladjustment in its bearing by a ring gear -32 which meshes with a common bevel gear 34 driven by the pivoted weights or other automatic adjusting means. The propeller mechanism thusfar described is 'no part of` our invention and hasY merely been selected as typical of adjustable pitch propeller mechanisms. In some instances, the blades of an adjustable pitch propeller are shifted to vary their pitch by an electric motor, hydraulic motor, orlother suitable manually or automatically controlled mechanisms and our invention is intended to be used with all types of variable pitchpropellers.

An internal combustion heater 36 is `located in the base of each propeller blade adjacent the root end I2 thereof. Each heater 36 comprises a combustion chamber 38 having a, cylindrical Wall 48 and an end wall 42. Combustible mixture is supplied to that portion of the combustion chamber adjacent the end Wall 42 by an induction tube 44 having a curved end 46 located in the combustion chamber and serving to preheat the mixture supplied thereto. The induction tube 44 is preferably of uniform diameter and discharges the combustible mixture in such manner as to create a ring of ame in the combustion chamber.

A housing 48 is attached to the cylindrical Wall 40 of the combustion chamber and provides a passage 50 in which a plug type of electric igniter 52 is located. The igniter 52 is of smaller diameter than the passage 50, so that an annular space is provided around the igniter for passage of combustible mixture therepast. Part of the combustible mixture delivered by the induction tube 44 flows through an inlet 54 into the lower end of passage 58 and is heated as it passes between the igniter 52 and the wall of the passage il. This mixture is ignited by the hot wire 55 located Yin the end of the igniter and the burning mixture passes from the passage 50 through outlet 56 into section 58 of the combustion chamber which is located between rings 60 and 62.

The ring 60 has an inwardly projecting portion 64 which is directed toward the wall 42 of the combustion chamber and tends to prevent liquid fuel from escaping from that portion of the combustion chamber Which contains the end 46 of the induction tube except by passing into the. passage 50, where it is vaporized by the igniter 52. The ring 62 tends to prevent the escape of any liquid fuel from the portion 58 of the combustion chamber and the combination of these rings effectively insures completecombusticn of all liquid fuel before this fuel can pass out of the combustion chamber.

Certain features pertaining to the construction and arrangement of the combustion chamber, induction tube and igniter are the sole invention of Henry J. De N. McCollum and are claimed in hisYco-pending applications, Serial No. 477,080, filed February 25, 1943, and Serial No. 478,258, iiledMarch 16, 1943.

Each induction tube 44 extends through a wall of a propeller blade and has an inlet end attached to a Venturi tube 6B. Each Venturi tube has a restricted throat into which fue] is discharged by a fuel jet 68 connected by a flexible hose I0 to a nipple 12 attached to4 a slinger ring l ring 14 to the burners located in these blades.

,Fuel is supplied to the slinger ring 14 by a stationary pipe 'I6 supported in a bracket 'I8 attached to any suitable part of the airplane engine or fuselage. The pipe 16 has a curved end 88 forming a spout located in the groove of the slinger ring 14 and delivering fuel to this ring as the latter rotates with the propeller blades. A second pipe 82 leads from an engine fuel tank or a separate fuel tank for the de-icer, as may be preferred, and is connected to the pipe 'I6 by Way of a solenoidcontrolV shut-off valve 84 and an altitude compensator 86 which varies the rate of flow of fuel to the slinger ring in accordance with variations in atmospheric density. Such altitude compensators are well-known and any suitable type may be used. The solenoid valve 84 is opened by closing a switch 88 in a circuit connecting this Valve with a suitable source of electrical energy, such, for example, as a battery 90.

The fuel delivered to each Venturi tube 66 by its associated jet 68 mixes with air entering the inlet or lefthand end of the Venturi tube to form a mixture of fuel and air which is delivered to a combustion chamber 42 through an induction tube 44. The inlet of each Venturi tube 66 is exposed to the pressure existing in the spinner 92. This spinner serves to protect the inlets of the Venturi tubes against dirt and moisture, but the interior of this spinner is in open communication with atmosphere and the pressure in this spinner varies with Variations in atmospheric pressure.

combustion chamber burns therein and is discharged into the interior of one of the hollow propeller blades I8 whereY it mixes with secondary air drawn into the interior of the blade through openings 94 located opposite the base of the combustion chamber and serving to connectthe interior of this blade with the interior of the spinner 92. This secondary air mixes with the hot products of combustion issuing fromthe combustion chamber and somewhat reduces the temperature of these products of combustion. The resulting admixture of products of combustion and secondary air then flows radially outward of the blades under the influence of centrifugal force and is discharged to atmosphere thro-ugh a suitable outlet of openings 96 adjacent the tip of the blade. Y

From the foregoing, it will be apparent that the action of centrifugal force on the products supply of fuel to the burners.

of combustion and secondary air is relied upon to move these fluids from the roots to the tips of the propeller blades. The same centrifugal force which causes this flow of gases toward the tips of the propeller blades also serves to draw combustible mixture into the combustion chambers and secondary air into the place through the openings 94. Centrifugal force acting on the. fuel in the flexible hoses I0 feeds this fuel toward the Venturi tubes 66 and jet 68 and the nipples 'l2 are preferably provided with restrictions 98 to insure even distribution of the fuel amongv the several burners and uniform rates of flow to these burners.

Each burner has a sufficient heat output to melt any snow and ice which may collect on itsV propeller blade and to maintain this blade throughout its entire surface area at a temperature above freezing throughout the atmospheric temperature range which is favorable to the formation of ice and snow on the propeller blades. When the atmospheric temperature is above freezing, no heat, of course, is requiredand the switch 88 may then be opened todshut off the Likewise, when the atmospheric temperature is Well below freezing and all moisture in the air is frozen in the form of snow or ice, there is no need to heat'the propeller blades and the control switch 88 should be in the open or off position. Our novel propeller de-icer is only needed when atmospheric temp-erature and humidity conditions are such that snow and ice tend'to accumulate on the propeller blades and thersolenoiduvalve 84 controlled bythe The mixture of fuel and air supplied to eachy manual switch 88- provides aA ready means for starting and stopping the operation of our pro-- peller de-icer.

The exhaust outlets at 'the tips of the propeller blades are preferably located at the extreme end, as is the outlet indicated by reference character 9.6. However, these outlets may, if desired, bel vlocated a short distance from the extreme end of the propeller blade, as is the outlet 96". This latter outlet is so positioned that the suction created by a propeller blade as it moves through the air .also tends to create a circulation through the. propeller blade. Since the pull of centrifugal force is sufncient to provide the requisite flow through the hollow propeller blade, the additional pull of suction is not required and the position ofthe outlet 96 has the slight disadvantage that a partially dead space is formed in the extreme tip of `the propeller blade where condensed moisture may collect. Either arrangement of the exhaust outlets, however, will provide satisfactory operation.

In the particular embodiment shown in the drawings, the igniters 52 are supplied from the same battery which furnishes the current for opening the solenoid fuel valve 84. Each igniter 52 has a wire |00 leading to a two part metal sleeve |82 which rotateswith the propeller hub I8. This two part sleeve is mounted on an insulating ring |04 interposed between the sleeve |02 and a supporting sleeve |08 attached to the hub I8 by bolts 20. Electricity is conducted to the sleeve |02 by a carbon contact |08 resiliently mounted in a stationary housing I I supported `in a bracket |II attached to the forward end of the engine or any suitable part of the airplane fuselage. A conductor II2 connects the brush to a push button switch |I4, which in turn isv connected to the battery 90 by wire IIS.

In order to prevent any sparks `formed at the contact |08 from igniting fuel in the slinger ring 14, we preferably provide a two part ring |02 with a radially extending ange I8 which forms a shield between the contact |88 and the slinger ring. It is understood that the wires |00 connecting the igniters with the ring |02 are sufciently flexible to permit the individual propeller blades to be rotated in the hub I8 to change the pitch of these blades without disturbing the electrical connections to the igniters.

Whenever it is desired to start the propeller deic'er, the pilot or a member of the airplane crew closes the switch 88 and presses down on the push button I I4. When switch 88 is closed, solenoid valve 84 opens and permits fuel to ilow to the jets 68. .As the fuel is discharged from these jets, it mixes with air entering the Venturi tube 68 and forms a fuel and air mixture delivered to the combustion chambers by way of induction tubes 44. As `soon as the pilot has closed the switch 88, he presses down on the push button I'I`4,`thereby closing the circuits tothe several igniters 52. In a few seconds, the hot wires 54 of these wires reach ignition temperature. Part ofthe fuel and air mixture delivered to the combustion chambers Venters the passages 50 surrounding the igniters 52 and is ignited by the hot wires of these igniters. The resulting combustion ignites all of the combustible mixture being supplied to the combustion chambers by the induction tubes 44 and as soon as this occurs a ringof flame is created in the base of each cornbustion chamber which suices to maintain combustion therein. The push button II4 may then be released to disconnect the igniters from their source of current.

When the induction .tubesy 44.1are. col'o:l,."sc me ofv the `fuel entering the combustion chambers,

may still be in liquid form. The rings prevent this fuel fromy passing from the .combustion. chambers directly into the blades -Ill` and deiiect this; liquid fuel into thel passagesr'ssurrounding the igniters 52. The heat of .these ig. niters vaporizes thisliquid fuel and forms a` rich mixture which may be readily set `on fire by the hot wires 55. If the push button. switch I| 4 l.is not closed immediately after the `switch88 is closed, the igniters 52 remain cold and liquid fuel enteringV the passages 50 may flow upwardly along the` walls of these passages and into the upper parts of the combustion chambers. Under-these conditions, the rings 62 will prevent the escape,

bustion of the gases prior to discharge of these gases from the outlet ends of the combustion chambers.

The gases discharge from the combustion chambers and mix with secondary air admitted through the openings 94 in the bases of the propeller blades and the admixture thus formed. then flows lengthwise of these blades. This ad,-

vmixture is hottest adjacent the discharge ends` of the combustion chambers and gradually; cools as it travels lengthwise of the propeller blades. However, the rate of transfer between these gases and the walls of the propeller blades varies with the rates of flow of these` gases, being` greatest where the rates of flow are greatest. The crosssectional areas of the hollow interiors of the propeller blades decrease from a maximum adjacent the roots of these blades to a minimum adjacent the tips 4of these blades, so that the rate of heat transfer from the gases to 4the blades tendsto increase as the gases approaches the tubes due toI the greater rate of ow of these gases.

. Our new and improved propeller de-icer .is particularly adapted for cie-icing airplane propellers of the adjustable pitch type, but it is also equally useful in de-icing fixed types of airplanel pro-` pellers and also propellers used for driving sleds or for any other purposes where the propeller is exposed to temperature and humidity conditions which favor the accumulation` of ice or snow onI the propeller blades. A

While we have shown and described only single embodiment of our invention, it is to be un derstood that our invention is not limited to the details shown and described, but mayassume` numerous other forms and that the scope of our invention is dened by the following claims.

We claim:

1. A propeller de-icer, comprising a propeller having a hollow blade, a combustion chamber rotatable with said propeller and supplying hot products of combustion to the interior of said blade, a stationary source of fuel for said combustion chamber, a rotating U-shaped ring movable with said propeller, a connection for con-V ducting fuel from said source to said ring, a carburetor for said combustion chamber, a connec- .tion between said ring and said carburetor, and means for igniting combustible mixture supplied to said combustion chamber by said carburetor.

2. De-icing means for a hollow propeller blade, comprising a cup-shaped combustion chamber having a base located near the hub end of said. blade and an open end directed toward the tip of 3. Apparatus of the class described, comprising a propeller having a plurality of hollow blades rotatable about the axis of Va common drive shaft, an internal combustion heater for each of said blades, an electrical igniter attached to each of said heaters, a carburetor for each of said heaters, said heaters, carburetors and igniters being rotatable about said axis, a non-rotatable source of fuel for said carburetors, a slingerring rotatable with said blades about said axis, a connection between each carburetor and said ring, a. nonrotatable nozzle for supplying fuel to said slinger ring,"altitude responsive means for varying the rate of fuel flow to said slinger ring, asolenoid valve for cutting off the ow of fuel to said ring, a manual switch for controlling said valve, a nonrotatable source of current for said igniters, a rotating ring electrically connected to all igniters, astationary brush contacting said ring and connected'to a source of current, and a push button controlling electrical connection between said brush and said source.

I4i. Apparatus of the class described, comprising a propeller having a plurality of hollow blades rotatable about the axis of a common drive shaft, anv internal combustion heater for each of said blades, an electrical igniter for each of said heaters, a carburetor for each of said heaters, said heaters, carburetors and igniters being rotatable about said axis, a non-rotatable source of fuel for said carburetors, connections between said carburetors and said source, a solenoid valve for cutting loil the flow of fuel to said carburetor, a manual switch for controlling said valve, a nonrotatable source of current for said igniters, a rotating ring electrically connected to all igniters, a stationary brush contacting said ring and connected to a source of current, and a switch controlling electrical connection between said brush and said source.

.5. Apparatus of the class described, comprising a propeller having a plurality of hollow blades rotatable about the axis of a common drive shaft, an internal combustion heater for each of said blades, an electrical igniter for each of said heaters, a carburetor for each of said heaters, said heaters, carburetors and igniters being rotatable about saidaxis, a non-rotatable source of fuel for said c'arburetors, a slinger ring rotatable Withsaid blades about said axis, a connection between each carburetor and'said ring, a solenoid,

heater for said blade, an electrical igniter for said heater, a carburetor for` said heater, said heater.;y carburetor and igniter being rotatable aboutsaid axis, a non-rotatable source of fuel forV said carburetor, a slinger ring rotatable with said blade, about said axis, a connection between each car buretor and said ring, a non-rotatable nozzleV for supplying fuel to said slinger ring, va solenoid valve for cutting off the ilow of fuel to said ring, a manual switch for controlling said valve, a' non-rotatable source of current for said igniter,- a rotating ring electrically connected to said'I igniter, a stationary brush contacting said ring` and connectedto a source of current, and manual. means controlling electrical connection between said brush and said source.

'7. 13e-icing means for a hollow propeller blade, comprising a cup-shaped combustion chamber having albase located near the hub end 0f said blade and an open end directed toward the Atip of said blade, aninduction tube extending through a wall of said blade, a carburetor connected to the outer end of said induction tube, means for supplying fuel to said carburetor, ahousing atV tached to a side wall of said combustion chamberl and having a passage connected at opposite ends tosaid combustion chamber, an electrical igniter located in said housing, and a ring for deflectingliquid fuel from said combustion chamber intov said passage. n f

8. Apparatus for de-icing a hollow blade propeller, including in combination, a combustion chamber mounted within and rotatable with said propeller and supplying hot products'l of combustion to the interior of said blade, a Venturi tube secured to the blade having-an inlet opening communicating with atmosphere and an outlet opening within said combustion chamber, and means including a conduit rotating with the blade having an outlet opening for supplying fuel to Venturi tube and air inlet, an annular passage'l rotatable with the propellerconnected to said inletfand a xed conduit associated with said annular passage for `supplying fuel to the combustion chamber.

9. De-icing apparatus for a hollow propeller' blade, including in combination, a cup-shaped combustion chamber having a base located near the hub end of said blade and an openend directed toward the tip of said blade, meansiforv supplying carbureted fuel to the interior'of. said'combustion chamber and near its base, meansin'cluding an igniterand a conduit in which'said igniter, is located communicating with said combustion chamber near its closed and open ends, and a4v ring secured inside said combustion chamber be-v tween the ends of said igniter containing conduit' for deecting (liquid fuel from said combustion' chamber into said conduit. i

10. Apparatus for de-icing a hollow blade pro-y peller, including in combination, a cup-shaped combustion chamber, mounted within the pro-A peller bladeA and havingv a base located near the hub end of said blade and an open end ydirected toward the tip of saidA blade, means including an induction tube discharging into said chamber adjacent the base of said cup for supplyingfuel to 'slaidchamben a pair vof fueldefiectorririgs located between said basean'd theopenend of saidy cup, each .of said rings having inwardly pro-'V` jecting inclined flangeslfor preventing escape of liquid fuel-from saidcombustion chamber, a Vbypass passage located around the ring nearest' the base, and anv igniter located in said by-pass pas` sage.

11. Apparatus for de-icing a hollow blade propeller, including in combination, a combustion chamber rotatable with said propeller and supplying hot products of combustion to the interior of the blade, means including a stationary fuel jet and an annular inwardly opening ring facing the jet and rotatable with the propeller for sup.- plying fuel to the ring, a carburetor rotatable with the combustion chamber, and a fuel connection between said ring and said carburetor for supplying fuel from said ring to said carburetor.

12. An internal combustion heater, comprising a cup-shaped combustion chamber through which liquid fuel tends to escape, a secondary air chamber surrounding said combustion chamber into which the products of combustion from the open end of said cup-shaped chamber ow, an induction tube for supplying combustible mixture to said combustion chamber, said induction tube discharging into said combustion chamber adjacent the base of said cup, a pair of spaced apart rings located between said base and the open end of said cup, each of said rings having inwardly projecting inclined flanges for preventing escape of liquid fuel from said combustion chamber, a 25 by-pass passage around one of said rings, and an ignter located in said by-pass passage.

LYNN A. WILLIAMS, J R. HENRY J. DE N. MCCOLLUM.

REFERENCES CITED The following references are of record. in the le of this patent:

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